Slip clutch



Jan 30, 1951 R. G. KRUEGER ET AL 2,539,630

SLIP CLUTCH Filed Jan. l2, 1946 /f zo Patented Jan. 30, v1951 sLIP CLUTCH Robert G. Krueger, Milwaukee, and Ralph N. Kircher, .West Bend, Wis., assignors to West Bend Aluminum Company, West Bend, Wis., a corporation of Wisconsin Application J anuary 12, 1946, Serial No. 640,769 4 claims. (ci. 644-28) This invention relates to slip clutches or flexible couplings, particularly the type used for driving propellers.

In devices of this type, a resilient member of rubber-like material engages both the driving Y and driven elements and permits slippage therebetween when the torque'load becomes excessive.k However, if such slippage occurs too 'frequently or is of too longv duration, the resilient material becomes permanently distorted, worn, or destroyed and will not restore motion to both elements after the excessive torque load has been removed. This condition cannot be re-y medied except by replacement of the resilient member.

It is the object of this invention, therefore, -to provide a slip clutch which permits the driving and driven elements to be inter-engaged for direct driving relationship whenever the resilient member fails to perform its function under normal torque load.

This object is accomplished by providing a set of teeth or the like in the driving or driven element which will intert with a similar set` of teeth or the like in other of such elements whenever thosev elements are moved axially relative to each other. Such axial movement is controlled by the removal of a spacing member such as a washer. Whenever the resilient member becomes ineffective to transmit normal torque force, it may be removed along with the spacing member and the elements shifted axi ally relative to each other to the position where the teeth are in driving engagement.

This invention has utilization in any number of applications for slip clutches. It has particular utilization in slip clutches used with propellers forv outboard motors. Very often the resilient member of these clutches breaks down at times when it is dangerous and inconvenient for the user to be without propelling power. By a very simple expedient, driving power may be temporarily restored to propeller without the necessity of replacement parts.

The novel features, which are considered characteristic of the invention, are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and its method of operation, together with additional objects and advantages thereof, will best be understood from the following description of a specific embodiment when read in connection with the accompanying drawing,

in which:

Figure 1 is a sectional view of the underwater portion of an outboard motor having a slip clutch, between the driving element and the idriven propeller, embodying the presentinvenion; l

Figure 2 is a sectional view taken on the line 2-2r of Figure 1;

Figure 3 is a sectional view taken on the line 3-3 of Figure l; and

Figure k4 is a sectional view of the device viewed in Figure l with the resilient member and spacing washer of the slip clutch removed and the propeller moved axially into direct interengaging relationship with the driving element.

Referring to the drawings by reference numerals, the clutch is shown embodied in the underwater leg of an outboard motor. The gear housing I0 and gear housing cover II rotatably support the propeller driving shaft L 2 in amanner well known to those skilled in the art. The shaft I2 protrudes rearwardly from the cover I I and there are present the customary washers and water seals, designated generally. at I3, which act as a stuffing box for the shaft I2. A propeller driving -member I4 has a central bore which permits it to slip over the end of the shaft I2. The member I4 has an intermediate outer peripheral surface formed with undulations I5.

.These undulations are pressed into the central opening of a resilient member I6 and form a driving connection between member I6 and member I4 which will not slip under normal torque transmission requirements. The member I4 also has at its forward end (the left as viewed in Figures 1 and 4) a peripheral flange, the outer surface of which is provided with a series of teeth I'I (see Figure 2) which interengage with teeth formed on the hub of the propeller to provide a direct drive when required. The member I4, at its rearward end, is provided with a portion forming an axle 2| for the propeller.

A shear pin I8 carried by the shaft I2 rests in a slot I9 formed in the member I4 to provide a driving connection between the shaft I2 and said member. y

The hub 20 of the propeller has a bore 26 which rotatably fits on the axle 2I to support the propeller. The hub 20 is also provided with a counter-bore 22 immediately adjacent the bore 26. The counter-bore 22 receives a spacing `washer 23 which prevents the hub from moving axially on the axle 2I far enough to the left to permit engagement between teeth I1 and the teeth on the hub 20. Adjacent'Y the counter-bore 22 is'another counter-bore 24 the inner surface of which is provided with a series of teeth 25. The teeth 25 terminate short of the forward (left-hand) end of the counterbore 24 to provide operating space in the counter-bore 24 for the teeth I'I to permit free angular movement between teeth I'I and teeth 25. The teeth 25, of course, engage the outer surface of the resilient member I6, to form a non-slip torque transmission connection therebetween. The hubf 243i is held on. the axle 2Iv by the usual cap nut 2 threaded on the shaft I2 and retained in position by a cotter pin 29. A washer 28 may be interposed between the nut and the end of the hub 20.

As shown in Figure l, the spacing- Washer 23 maintains the hub 20 spaced axially to therear.-

(right as viewed in Figure l). of' the propeller to prevent the teeth I'I from having engagement with the teeth 25. element I6 transmits normal torque from the member I4 to the hub 2). If for some reason the propeller should become snared and require more than'. the normal predetermined torque toY turn it, then a slippage occurs between; the; member I 4 and the resilient member It. This slippage will avoid the breakage of; the;v shear pin; I8; and

of the. propeller. However, if slippage occurs too frequently or endures for tool long a. period of time, the member IS becomesl so. worn, distorted -orchewed-up that it willV no; longer engage the undulations t5. tightly enough tov cause-a. transmittal of normal torque from the member I4; to the resilient member- I6. When such a condition occurs, itl is only necessary toremovethe cap nut 27 and the propeller hub 2B, take out the resilient member I8v and the spacing` washer 23,

and then reassemble the propeller hub 201011 the l axle 2I. In this reassembly, which is shown in Figure 4, the hub 2t. isI shifted axially forward @toward the left as viewed in the drawings). This causes the teeth Il to 'become directlyV interengaged with the teeth 25, thusA creating a positive` drive between the member I4 andthe hub ZB. This positive drive is accomplished without the'use of anyv replacement parts,v suchfras the resilientA member I, andl hence may: be accomplished evenA though-such` replacement parts are not available at the timerthe condition arises.

The directf drive, ofcourse, is a temporary expediency and as soon. as possible the defective resilient member Itl should be replaced; However, the shearpin i8 provides some protection against damageto the propeller even during this temporary direct drive relationship.

Although only one embodiment o-f the invention is shown and described herein, itwill be understood that this application is intended to cover such changes or 'modications as4 come 'within the spirit of the inventionorscope o-f the following claims;`

We claim:

1-. A slip clutch comprisingl a propeller shaft having thereon a propeller drivingmember, said member being providedwith a series of undula- -tionsi adapted to engage the inner surface of a resilient member, a shear pin carried by said shaft' and having a driving engagement with said propeller` driving member, a propellerv havingY aV hub rotatably mountedA on said' propeller driving member, said hubhavi-ngan inner periphery provided with teethadaptedV to engage the outer surface of a resilient member, a resilient member mounted between said teeth and said unduiations to transmit torque from said; member to said hub, said member having a peripheralv por- In this,4 position the resilient,y

4 tion provided with teeth adapted to engage with the teeth in said hub when said member and hub are moved axially into alinement, and a spacer interposed between said member and said hub to maintain the teeth on said hub spaced from the teeth on said member and out of driving engagement-.therewith l 2; A slipclutch comprisingl'adriving element having formed thereon a series of undulations and a hub-carrying axle, a propeller including a hubv having a portion rotatably mounted on said axle, a series of teeth formed on the interior portionvof.: said hub, a resilient member in close contact with saidf undulations and said teeth to transmit normal torque between said element and said hub, and a series of teeth on said element in alinement with the teeth on said hub and engageable therewith upon lateral movement of said -hubvrelative to said element.

3. A slip clutch comprising a driving element 'having-Y formed thereon a` series, of undulati'ons Aally spacedl from the teethA on said'elementrr.

4. A slip clutch comprising a driving element having a surface provided with means for making a driving connection with a resilient member Which-will not slip under normalv torque transmission requirements but will slip when more than normal torque is applied, aresilient member mounted on said sur-face and interconnected with teethona driven element, teeth on said driving element adjacentA saidI surface, saidV teeth being free of driving connectionv with said resil'ient member and adapted to interengage with i teeth on a dri-ven element, adrivenI element provided with teethY interconnect'edwi-th sai'dl resilient member to providenon-slip torque transmission therebetween, saidv teeth in thenOrmal" relationship of said driving and driven vele;- ments being'spaoed from the teeth on said driving element, a non-resilientmember normallyin'ter'- posed between said driving and' driven elements toY maintain the teeth on said elementsl spaced, said non-resilient member being removable to permit said elements to move together and the teeth thereof'to, interengage and form a nQneslip connection between said' driving and driven element, and adjustable means forv holding said el'ements in bothnormal relationship 'with said' teeth spaced' and in positive drive relationship 'l with saidI teeth interconnected'. 1

ROBERT G.. KRUEQERT RALPH N L, KIRCHER..

REFIERENGESY CITED The following references are ofV ,record in-. the

le of this patent:

UNITED STATES PATENTS. 

